HDOJ 2156 分数矩阵(水题)

HDACM 2156

import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        double[] sum = new double[50000];
        double s = 1;
        sum[1] = 1;
        for (int i = 2; i < sum.length; i++) {
            s += 2.0/i;
            sum[i] = sum[i-1]+s; 
        }
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            if (n==0) {
                break;
            }
            System.out.printf("%.2f",sum[n]);
            System.out.println();
        }
        sc.close();
    }
}